写个算法判断给定的字符向量是否为回文

Question

执行代码后段错误
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXSIZE 20
typedef char ElemType;
typedef struct Stack
{
ElemType top;
ElemType base;
int Stacksize;
}Stack,StackLink;
//初始化一个栈
void InitalStack(StackLink S)
{
S->base=(ElemType)malloc(MAXSIZEsizeof(ElemType));
if(S->base==NULL)
printf("创建错误\n");
S->base=S->top;
S->Stacksize=MAXSIZE;
}
void Pop(StackLink S,ElemType e)
{
if(S->base==S->top)
printf("栈为空，出栈错误\n");
else
{
e=--S->top;
}
}
void Push(StackLink S,ElemType e)
{
if(S->top-S->base==MAXSIZE)
printf("入栈错误\n");
else
{
*S->top++=e;
}
}
//判断空栈
int StackEmpty(StackLink S)
{
return(S->base==S->top);
}
int IsPlalindrome(ElemType *a)
{
StackLink S;
ElemType e;
InitalStack(S);
int len,i;
len=strlen(a);
//入栈
for(i=0;i<len/2;i++)
{
Push(S,a[i]);
}
//回文数的长度为奇数
if(len%2==1)
i++;
//将剩余的字符与栈中的字符进行比较，相同则出栈
while(!StackEmpty(S))
{
Pop(S,e);
if(e==a[i])
i++;
else
return 0;
}
return 1;
}
int main()
{
char a[MAXSIZE];
gets(a);
if(IsPlalindrome(a))
printf("YES\n");
else
printf("No\n");

return 0;

}

Answer 1

代码修改如下：
运行结果：

代码：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXSIZE 20
typedef char ElemType;
typedef struct Stack
{
    ElemType *top;
    ElemType *base;
    int Stacksize;
}Stack,*StackLink;
//初始化一个栈
void InitalStack(StackLink S)
{
    S->base=(ElemType*)malloc(MAXSIZE*sizeof(ElemType));
    if(S->base==NULL)
        printf("创建错误\n");
    S->top=S->base;//S->base=S->top;  //修改1
    S->Stacksize=MAXSIZE;
}
void Pop(StackLink S,ElemType *e)
{
    if(S->base==S->top)
        printf("栈为空，出栈错误\n");
    else
    {
        --S->top;
        *e=*(S->top);
    }
}
void Push(StackLink S,ElemType e)
{
    if(S->top-S->base==MAXSIZE)
        printf("入栈错误\n");
    else
    {
        *S->top++=e;
    }
}
//判断空栈
int StackEmpty(StackLink S)
{
    return(S->base==S->top);
}
int IsPlalindrome(ElemType *a)
{
    StackLink S=(StackLink)malloc(sizeof(Stack)); //修改
    ElemType e;
    InitalStack(S);
    int len,i;
    len=strlen(a);
    //入栈
    for(i=0;i<len/2;i++)
    {
        Push(S,a[i]);
    }
    //回文数的长度为奇数
    if(len%2==1)
        i++;
    //将剩余的字符与栈中的字符进行比较，相同则出栈
    while(!StackEmpty(S))
    {
        Pop(S,&e);
        if(e==a[i])
            i++;
        else
        {
            free(S);//释放空间
            S = 0;
            return 0;
        }
    }
    free(S);//释放空间
    S = 0;
    return 1;
}
int main()
{
    char a[MAXSIZE],*p;
    p = gets(a);//或者 p = gets_s(a);
    if(IsPlalindrome(a))
        printf("YES\n");
    else
        printf("No\n");

    return 0;
}